Purrified Air made some new friends at Floppy Cats (floppycats.com).
From the attached article and review:
"I always have to turn on the light to see if the cats have peed or pooped and one of them has. So, it does a good job. There's nothing you can smell."
"I'm actually excited about this product not only for litter box smells but it's a carbon filter so it's going to get rid of basement smells too."
"I had my sprinkler guy come over and winterize my sprinkler. He came down (into the basement) to three litter boxes. I said, can I ask you something? He said 'sure.' Does it smell like cats at all?. He said 'no, not at all'."